I. Field of the Invention
The invention concerns a method of operating a stationary power plant, wherein a fuel/air mixture is burned in an internal combustion engine and the internal combustion engine drives an alternating current generator, wherein the alternating current generator is connected to an energy supply network and delivers energy to the energy supply network.
The invention further concerns a stationary power plant including an internal combustion engine having at least one ignition device, and an alternating current generator which is operable by the internal combustion engine, wherein the alternating current generator in the operating condition is connected to an energy supply network and delivers energy to the energy supply network and the energy supply network predetermines the reference voltage and the reference frequency of the alternating current generator.
II. Description of the Related Art
Stationary power plants are frequently used in the so-called network parallel mode, in which case they feed energy into the power supply network (integrated grid network). Stationary power plants according to the invention include an internal combustion engine in which fuel is burnt in the presence of air and an alternating current generator driven by the internal combustion engine. In particular gas engines, that is to say internal combustion engines which are operated using the Otto cycle with a gaseous fuel are suitable for such stationary power plants as they have a high level of efficiency and low pollutant emissions. In the state of the art the energy supply network predetermines the reference voltage and the reference frequency of the alternating current generator. If there is a voltage drop in the energy supply network, that involves a cessation in that presetting of reference voltage and reference frequency, the consequence thereof being that the rotary speed of the internal combustion engine and as a further consequence also that of the alternating current generator rises rapidly by virtue of the removal of the resistance due to the energy supply network. Admittedly regulating concepts are certainly already known in which the increase in speed of the internal combustion engine is reduced by the fuel supply thereto being reduced, but the short-term increase in the speed of the internal combustion engine and the alternating current generator leads to a phase shift in the delivered ac voltage in comparison with the energy supply network. If the network failure is only in the short term and the energy supply network were then switched on again, that would involve a confrontation with a phase shift which self-evidently is undesirable. In practice therefore the procedure has changed over to interrupting the connection between the energy supply network and the alternating current generator and switching on the alternating current generator again, when the network is restored, only when phase coincidence prevails. Statutory presetting requirements are intended to prevent an interruption in the connection between the energy supply network and the alternating current generator.